Wierd Block Learn Value?
Thread Starter
Pro
Joined: Feb 2002
Posts: 565
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From: Chandler AZ
Wierd Block Learn Value?
On cold startup my left learn block value is 155-160 and car runs like crap. Surges up and down with fuel smell (rich) for about 10-12 minutes and then the BLV goes to 128 like the right side. At the same time the injectors on the left side are pulsing at ~ 1 ms more then the right. After it warms up it's fine. Any ideas? I could really use the help. Maybe the PCM? Thanks, Robert 94 auto. w/ 215,000 miles 
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
Verify that it's Closed Loop. If it stays at 155 to 166 for more than a minute or so, it should set a Code 44. However, those numbers mean that the left side is extremely lean. The PCM adds fuel and since you're sensing that it's too much fuel, air may be getting into the exhaust stream. I'd start be pinching off the left side air pump hose where it connects to the header. If the left side #'s drop, the air pump circuitry is faulty or the check valve may be defective. The check valve can be removed to verify that it only allows air to flow in the direction of the header. If the #'s don't improve, it could be that one of the O2 signal wires is shorted to ground. Disconnect the harness and jumper the low side - tan/white (PCM side) - to ground. Your scanner should show a steady .35 to .55 volts. If not, there's a short to ground in that circuit or the PCM is bad. Should that check out, then I'd suspect a lean injector. Ohm out the injector coils hot and cold. All should be about 17 ohms.
Thread Starter
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Joined: Feb 2002
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From: Chandler AZ
It stays bad after it goes into closed loop. Air pump shuts off after 2 minutes so shouldn't be a factor. Will check injectors for ohms. Could one injector cause this? The O2s are showing normal numbers, low to high to low, so I think that they are OK. I'm still leaning toward the PCM but don't want to just throw parts at it if I can avoid it. Thanks, Robert 
No code show on my AutoXray unit.
No code show on my AutoXray unit.
Last edited by Quiktrp94; Sep 18, 2005 at 11:35 PM.
Le Mans Master
Joined: Dec 2004
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From: Myrtle Beach SC
St. Jude Donor '05-'06
When was the last time you had the injectors sent to be cleaned /or replaced?The O2 might be out of cal it may be reading wrong and sending bad feedback to the computer.That would be my first choice as they should be replaced every ~50k anyway.Use Delco not bosche. So it is either a sticky/bad injector,bad O2 or possibly a bad plug/wire but you did not say it ran bad.You might try a bottle of Techron cleaner in your gas and re-check your readings.
Last edited by Redeasysport; Sep 18, 2005 at 11:58 PM.
Thread Starter
Pro
Joined: Feb 2002
Posts: 565
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From: Chandler AZ
Thanks for the replies. The injectors were bought from FiveO about a year ago, But that doesn't mean that 1 or 2 couldn't be bad. Will check. The O2s are about 1 1/2 years old and seem to be working ok. They both change from high to low mv as normal. Plugs are 4years and 30,000 miles old.Wires are new with the Delteq unit. It's not the delteq, Was doing it beforeI installed it. Thanks
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
Don't think so. It's a one way valve that allows air to flow to the headers when the air pump is diverting air in that direction (which it does on start up to get the O2's and CAT up to operating temp). If the check valve is broken, exhaust can flow back towards the pump and it can suck air into the exhaust stream. And, if the air pump diverts air to the headers after closed loop (ie, it stays on too long), it will cause the symptoms you describe. If it checks out and the O2 and injectors are ok, the only other things I can think of that might be causing your problem would be an actual header leak or the valve train. I don't think it's a vacuum leak as you would see it on both sides.
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Thread Starter
Pro
Joined: Feb 2002
Posts: 565
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From: Chandler AZ
Well I pinched off the EGR tube and it did the same thing. Also checked the injectors and all have 17 ohms resistance cold. This starts as soon as I start the car and continues for about 10 minutes and then it runs fine. Just to throw out something else I still have the problem of AC voltage from my alt. to ground and someone had posted on another thread that the AC could be messing up the PCM. I am going to check with the place that I bought it from about that.It puts out ~30 VAC!!!!
